mask created in Lightroom mobile must be manually updated in Lightroom Classic

Some masks which I have created in Lightroom cc (mobile, i-Pad 8.2.2) are not transferred correctly to Lightroom classic (12.2.1) and then must be newly calculated; manually.  This happens also the other way round from classic to cc.  Not each masking is effected, I can not see any pattern.

I would like to understand how to avoid this. And if it is a "bug" how can I simpley find not correctly calculated masks without checking each and every picture ?